Commodity rubber is used for sealing and insulation in many consumer, commercial, and industrial applications. Examples include the door seals and window seals on heavy equipment. Part of the reason for commodity rubber’s popularity is that compounds like commercial grade EPDM, silicone, and neoprene cost less than specialty rubber that meets standards, approvals, or regulatory requirements from organizations such as ASTM International, Underwriters Laboratories (UL), and the U.S. Food and Drug Administration (FDA).

With today’s supply chain disruptions, it’s more important than ever to understand when a specialty rubber is truly required and a commodity rubber would be sufficient. Engineers want to design the best products possible but over-specifying an elastomer can add unnecessary costs to projects. With specialty rubber, you’re not just paying more per unit of material. Typically, you also need to buy larger minimum order quantities (MOQs). For your company, this ties up cash and may require storing more material in an already crowded warehouse.    

In this article from Elasto Proxy, we’ll consider the differences between commodity rubber and specialty rubber in terms of a few real-world examples. You’ll also learn when what you ask for puts you at risk of not getting what you really need. Keep reading to learn more or contact us to find out how we can help you solve sealing and insulation challenges. Elasto Proxy supplies coils of commodity or specialty rubber, cut lengths, custom seals, finished gaskets, thermal-acoustic insulation – and much more.

Example #1: ASTM Rubber

Sometimes, engineers ask us for “ASTM rubber” or for a material that “meets ASTM D 2000”. These questions are on the right track but won’t get the proverbial train to the station. For starters, there isn’t a single ASTM test standard for rubber materials. In fact, there are many different testing standards. For example, do you need a rubber that meets the minimum liquid leakage requirements of ASTM F 37-06(2013)? Do you need a rubber that meets ASTM F433-02(2014)e1 for thermal conductivity instead? Before deciding that you need a specialty material then, talk to us about your application.

So, what about ASTM D 2000? Why can’t you just ask for a rubber that meets it? ASTM D 2000 isn’t a testing standard but rather a published specification that provides a standard way to describe vulcanized elastomers. In other words, it defines the language of rubber. Asking for “ASTM D 2000 rubber” instead of “ASTM rubber” might seem more specific, but it’s not. It’s like going to a heavy equipment distributor and asking for the “big machine” instead of the “machine” without indicating whether you need a truck, tractor, or something else.  

Example 2: UL 50 Gaskets

UL 50 is a standard from Underwriters Laboratories (UL) that applies to enclosures for electrical equipment that will be installed and used in non-hazardous locations in accordance with national electrical codes in Canada, the United States, and Mexico. UL 50 applies to the entire enclosure and not to individual components such as seals, gaskets, and insulation. In fact, UL 50 states that if an individual product (e.g., a seal or gasket) has requirements that are at variance with UL 50, the requirements for the individual product take precedence.

Sometimes, however, engineers ask for “UL 50 gaskets” when a UL 50 approved material really is not required. There are several issues here. First, a well-designed enclosure may be able to meet UL 50’s requirements without the use of more expensive UL-approved gasket materials. Second, there is a separate UL standard (UL 50E) for the environmental construction of qualifying environmental enclosures. During the design process then, you may need to account for two separate but related standards. If the electrical enclosure is for an appliance, then the UL 94 flame rating standard may apply instead.

Ask Us About Commodity Rubber vs. Specialty Rubber

Unfortunately, asking for a “black rubber” or putting “UL 50 gasket” or “ASTM rubber” on your schematic probably won’t get you what you need. That’s why when you work with Elasto Proxy, we’ll offer to help you not just with material selection, but with seal design as well. If you use a CAD application like SolidWorks®, we can send you DWG files of standard profiles that you can drop into your design. We can send you PDF versions of our standard profiles, too.

Are you wondering whether you need commercial grade rubber or specialty rubber for products like the gaskets on heavy equipment or electrical enclosures? Do you have questions about seal design as well? Don’t wait until your design is almost complete to begin thinking about sealing. Otherwise, you might need to use specialty rubber because a commercial grade compound can’t support a design constraint. By talking to our team earlier in your design process, you can make life easier.e

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